RESIST-3 O.K.N. - FAQ

What is the effect of zinc for the detection of NDM by test RESIST-3 from Mueller-Hinton agar (MHA) ?

When MHA plate was supplemented with 100-μl 10 mM zinc sulfate by spreading, the NDM band was more intense and became visible faster (see article A. Saleh et al. in JCM, 2018).

What are the variants that are recognized by our RESIST tests?

What are the bacterial species tested for the different carbapenemases of our tests?

Can the antibiogram be used as a sample for RESIST-3?

Yes. Taking 1-μl around the ertapenem, imipenem and meropenem disks and dilution in 10 drops of LY-A buffer allows the detection of OXA-48, KPC and NDM carbapenemases in 100% of cases, while maintaining 100% specificity.

What are the culture media compatible with the kit?

Is the buffer the same for all Coris BioConcept's K-SeT kits? If I need some more for my tests, may I use the one from another kit?

According to the "Instructions For Use" it is not allowed to exchange buffer between kits. If you face some volume problems, please contact your distributor. He will provide you with some more vials. Nevertheless, for one product, the buffer is always the same; so, for instance, using the HC Dilution Buffer from different Combi K-SeT lots will not give rise to any problems on the strips as long as those buffers are within their shelf-life range as indicated on the vial.

What happens when a clinical specimen is a strongly positive specimen? What about the control line?

There are two different kinds of conjugates – a specific reagent for test line and a specific reagent for the control line - in the strip. A strong positive specimen has NO effect on the intensity of the control line onto the nitrocellulose of the strip. As long as the control line appears - with whatever intensity level - the test should be regarded as valid.

Why does the control line sometimes appear very weak while the test line is positive?

Control line is aimed to ensure that chromatography has been performed up to the top of the strip. It is not related with the result of the diagnostic itself.

Sometimes, the control line might be "slightly weak "without any precise reason. It could be only an effect of the sample migration and / or responsiveness at the control line. The control line is aimed to validate the test using various specimen.

How to use correctly K-SeT kits from Coris BioConcept?

Always store the reagents at the indicated storage temperature : between 4 and 30°C for all kits

Aways use gloves to manipulate kit components and samples

Always use the provided (Extraction, Dilution, …) Buffer even if the sample is already diluted (e.g. in a transport medium)

Always be sure that the solution sample – buffer is homogenous before testing

Always read the results when the dipstick into the device is wet (between 10 and 15 minutes depending on the test

How long can a pouch remain open before performing the test?

Once the pouch is opened, the test should be performed immediately. An unopened pouch may be kept at between 4 and 30°C and used until the shelf-life date indicated on the packaging.

The liquid does not migrate in the cassette, what should I do?

The most plausible hypothesis to explain the invalid test (no control line after running) is a problem of sample volume poured into the sample well of cassette.

In the notice, the instructions for use stipulates to dispense 3 drops of diluted sample delivered by the collection tube with dropper provided with the kit. However, if you put only 2 drops of diluted samples in tube, the conjugate may not be released completely from the pad where it is dried, and the reduced liquid volume does not allow a correct and complete migration on the strip in the cassette. We recommend to perform a new cassette test with 3 drops of preparation of diluted sample to recover the correct migration. Contact Coris (cc) if you encounter again this technical problem.

Is it a problem if the test has "run" more than the recommended time?

Yes. It might cause the appearance of false positive signal on test.

The signal of the test line is very weak in comparison with the control line. Do I have to consider that the result is positive?

The control line is aimed to ensure the user that the chromatography is performed up to the top of the strip. It does not give any indication on the diagnostic result. Whenever a signal is observed on the test line (weak or strong), it means that the result of the test is positive for the pathogen of interest.